Actual source code: ex31.c


  2: static char help[] = "Test partition. Reads a PETSc matrix and vector from a file and solves a linear system.\n\
  3: This   Input parameters include\n\
  4:   -f <input_file> : file to load \n\
  5:   -partition -mat_partitioning_view \n\\n";

  7: /*T
  8:    Concepts: KSP^solving a linear system
  9:    Processors: n
 10: T*/

 12: #include <petscksp.h>

 14: int main(int argc,char **args)
 15: {
 16:   KSP            ksp;             /* linear solver context */
 17:   Mat            A;               /* matrix */
 18:   Vec            x,b,u;           /* approx solution, RHS, exact solution */
 19:   PetscViewer    fd;              /* viewer */
 20:   char           file[PETSC_MAX_PATH_LEN];     /* input file name */
 21:   PetscBool      flg,partition=PETSC_FALSE,displayIS=PETSC_FALSE,displayMat=PETSC_FALSE;
 23:   PetscInt       its,m,n;
 24:   PetscReal      norm;
 25:   PetscMPIInt    size,rank;
 26:   PetscScalar    one = 1.0;

 28:   PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr;
 29:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 30:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);

 32:   PetscOptionsGetBool(NULL,NULL,"-partition",&partition,NULL);
 33:   PetscOptionsGetBool(NULL,NULL,"-displayIS",&displayIS,NULL);
 34:   PetscOptionsGetBool(NULL,NULL,"-displayMat",&displayMat,NULL);

 36:   /* Determine file from which we read the matrix.*/
 37:   PetscOptionsGetString(NULL,NULL,"-f",file,sizeof(file),&flg);
 38:   if (!flg) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_USER_INPUT,"Must indicate binary file with the -f option");

 40:   /* - - - - - - - - - - - - - - - - - - - - - - - -
 41:                            Load system
 42:      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 43:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,file,FILE_MODE_READ,&fd);
 44:   MatCreate(PETSC_COMM_WORLD,&A);
 45:   MatLoad(A,fd);
 46:   PetscViewerDestroy(&fd);
 47:   MatGetLocalSize(A,&m,&n);
 48:   if (m != n) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_SIZ, "This example is not intended for rectangular matrices (%D, %D)", m, n);

 50:   /* Create rhs vector of all ones */
 51:   VecCreate(PETSC_COMM_WORLD,&b);
 52:   VecSetSizes(b,m,PETSC_DECIDE);
 53:   VecSetFromOptions(b);
 54:   VecSet(b,one);

 56:   VecDuplicate(b,&x);
 57:   VecDuplicate(b,&u);
 58:   VecSet(x,0.0);

 60:   /* - - - - - - - - - - - - - - - - - - - - - - - -
 61:                       Test partition
 62:   - - - - - - - - - - - - - - - - - - - - - - - - - */
 63:   if (partition) {
 64:     MatPartitioning mpart;
 65:     IS              mis,nis,is;
 66:     PetscInt        *count;
 67:     Mat             BB;

 69:     if (displayMat) {
 70:       PetscPrintf(PETSC_COMM_WORLD,"Before partitioning/reordering, A:\n");
 71:       MatView(A,PETSC_VIEWER_DRAW_WORLD);
 72:     }

 74:     PetscMalloc1(size,&count);
 75:     MatPartitioningCreate(PETSC_COMM_WORLD, &mpart);
 76:     MatPartitioningSetAdjacency(mpart, A);
 77:     /* MatPartitioningSetVertexWeights(mpart, weight); */
 78:     MatPartitioningSetFromOptions(mpart);
 79:     MatPartitioningApply(mpart, &mis);
 80:     MatPartitioningDestroy(&mpart);
 81:     if (displayIS) {
 82:       PetscPrintf(PETSC_COMM_WORLD,"mis, new processor assignment:\n");
 83:       ISView(mis,PETSC_VIEWER_STDOUT_WORLD);
 84:     }

 86:     ISPartitioningToNumbering(mis,&nis);
 87:     if (displayIS) {
 88:       PetscPrintf(PETSC_COMM_WORLD,"nis:\n");
 89:       ISView(nis,PETSC_VIEWER_STDOUT_WORLD);
 90:     }

 92:     ISPartitioningCount(mis,size,count);
 93:     ISDestroy(&mis);
 94:     if (displayIS && rank == 0) {
 95:       PetscInt i;
 96:       PetscPrintf(PETSC_COMM_SELF,"[ %d ] count:\n",rank);
 97:       for (i=0; i<size; i++) {PetscPrintf(PETSC_COMM_WORLD," %d",count[i]);}
 98:       PetscPrintf(PETSC_COMM_WORLD,"\n");
 99:     }

101:     ISInvertPermutation(nis, count[rank], &is);
102:     PetscFree(count);
103:     ISDestroy(&nis);
104:     ISSort(is);
105:     if (displayIS) {
106:       PetscPrintf(PETSC_COMM_WORLD,"inverse of nis - maps new local rows to old global rows:\n");
107:       ISView(is,PETSC_VIEWER_STDOUT_WORLD);
108:     }

110:     MatCreateSubMatrix(A,is,is,MAT_INITIAL_MATRIX,&BB);
111:     if (displayMat) {
112:       PetscPrintf(PETSC_COMM_WORLD,"After partitioning/reordering, A:\n");
113:       MatView(BB,PETSC_VIEWER_DRAW_WORLD);
114:     }

116:     /* need to move the vector also */
117:     ISDestroy(&is);
118:     MatDestroy(&A);
119:     A    = BB;
120:   }

122:   /* Create linear solver; set operators; set runtime options.*/
123:   KSPCreate(PETSC_COMM_WORLD,&ksp);
124:   KSPSetOperators(ksp,A,A);
125:   KSPSetFromOptions(ksp);

127:   /* - - - - - - - - - - - - - - - - - - - - - - - -
128:                            Solve system
129:         - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
130:   KSPSolve(ksp,b,x);
131:   KSPGetIterationNumber(ksp,&its);

133:   /* Check error */
134:   MatMult(A,x,u);
135:   VecAXPY(u,-1.0,b);
136:   VecNorm(u,NORM_2,&norm);
137:   PetscPrintf(PETSC_COMM_WORLD,"Number of iterations = %3D\n",its);
138:   PetscPrintf(PETSC_COMM_WORLD,"Residual norm %g\n",(double)norm);
139:   flg  = PETSC_FALSE;
140:   PetscOptionsGetBool(NULL,NULL, "-ksp_reason", &flg,NULL);
141:   if (flg) {
142:     KSPConvergedReason reason;
143:     KSPGetConvergedReason(ksp,&reason);
144:     PetscPrintf(PETSC_COMM_WORLD,"KSPConvergedReason: %D\n", reason);
145:   }

147:   /* Free work space.*/
148:   MatDestroy(&A); VecDestroy(&b);
149:   VecDestroy(&u); VecDestroy(&x);
150:   KSPDestroy(&ksp);

152:   PetscFinalize();
153:   return ierr;
154: }

156: /*TEST

158:     test:
159:       args: -f ${DATAFILESPATH}/matrices/small -partition -mat_partitioning_type parmetis
160:       requires: datafilespath !complex double !defined(PETSC_USE_64BIT_INDICES) parmetis
161:       output_file: output/ex31.out
162:       nsize: 3

164: TEST*/